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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 237 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  2. 2.√66 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.1 (d) 8.3
  3. 3.Best estimate of 2749 ÷ 46? (a) 5500 (b) 550 (c) 55
  4. 4.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.9 (d) 5.8
  5. 5.Best estimate of 2121 ÷ 26? (a) 71 (b) 7100 (c) 710
  6. 6.√30 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  7. 7.Best estimate of 2994 ÷ 38? (a) 750 (b) 75 (c) 7500
  8. 8.Best estimate of 1671 ÷ 22? (a) 8400 (b) 840 (c) 84
  9. 9.Best estimate of 941 ÷ 62? (a) 1600 (b) 160 (c) 16
  10. 10.Best estimate of 701 ÷ 26? (a) 23 (b) 230 (c) 2300
  11. 11.√86 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  12. 12.Best estimate of 2389 ÷ 29? (a) 800 (b) 8000 (c) 80
  13. 13.√69 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  14. 14.Best estimate of 2792 ÷ 49? (a) 56 (b) 560 (c) 5600
  15. 15.√59 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.5
  16. 16.Best estimate of 4554 ÷ 71? (a) 6500 (b) 65 (c) 650
  17. 17.√78 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.7 (d) 8.9
  18. 18.Best estimate of 4159 ÷ 84? (a) 5200 (b) 520 (c) 52
  19. 19.√40 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.6
  20. 20.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.6 (d) 7.8
  21. 21.√50 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  22. 22.√58 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.6 (d) 7.8
  23. 23.√41 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.4
  24. 24.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.2
  25. 25.√62 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.9 (d) 7.7
  26. 26.Best estimate of 2594 ÷ 42? (a) 65 (b) 650 (c) 6500
  27. 27.√84 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.2
  28. 28.Best estimate of 1156 ÷ 63? (a) 190 (b) 19 (c) 1900
  29. 29.Best estimate of 2418 ÷ 38? (a) 60 (b) 6000 (c) 600
  30. 30.√90 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.5 (d) 9.4
  31. 31.Best estimate of 4655 ÷ 52? (a) 93 (b) 930 (c) 9300
  32. 32.Best estimate of 2437 ÷ 71? (a) 35 (b) 3500 (c) 350
  33. 33.Best estimate of 1836 ÷ 39? (a) 4600 (b) 460 (c) 46
  34. 34.Best estimate of 1519 ÷ 28? (a) 5100 (b) 51 (c) 510
  35. 35.√82 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  36. 36.Best estimate of 1675 ÷ 46? (a) 3400 (b) 34 (c) 340
  37. 37.Best estimate of 1749 ÷ 29? (a) 58 (b) 5800 (c) 580
  38. 38.√42 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.5 (d) 6.6
  39. 39.√94 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.7 (d) 9.6
  40. 40.Best estimate of 1804 ÷ 39? (a) 45 (b) 450 (c) 4500

Answer key

  1. 6.8
  2. 8.1
  3. 55
  4. 6.1
  5. 71
  6. 5.5
  7. 75
  8. 84
  9. 16
  10. 23
  11. 9.3
  12. 80
  13. 8.3
  14. 56
  15. 7.7
  16. 65
  17. 8.8
  18. 52
  19. 6.3
  20. 7.8
  21. 7.1
  22. 7.6
  23. 6.4
  24. 5.4
  25. 7.9
  26. 65
  27. 9.2
  28. 19
  29. 60
  30. 9.5
  31. 93
  32. 35
  33. 46
  34. 51
  35. 9.1
  36. 34
  37. 58
  38. 6.5
  39. 9.7
  40. 45

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